In a manufacturing process of semiconductor devices, a substrate polishing apparatus has been widely used for polishing the surface of a wafer. The substrate polishing apparatus holds the peripheral edge of the wafer with an annular retainer ring and presses the wafer against a polishing pad, thereby performing a polishing.
As the retainer ring is a consumable part that is worn out when the wafer is polished, it needs to be regularly exchanged with a new one. In addition, the polishing characteristic of a new retainer ring is not stabilized right after the exchange, and thus, the new retainer ring is generally initialized by polishing a dummy wafer.
See, for example, Japanese Patent Laid-Open Publication Nos. 2005-11999, 2007-27166, 2007-296603, and 2007-511377.